Subtle, fleeting differences in ocean salinity or temperature can act as physical barricades for phytoplankton, which results in a patchy distribution of the most important food resource in the ocean and may explain the large biodiversity in the sea. Ocean currents transport phytoplankton, or microscopic algae, that float in the sea. And researchers say the composition of phytoplankton communities affects other microscopic organisms, fish and even whales, as phytoplankton constitutes the base of the food web in the sea. [Source: UMaine News]